Date palms of any age may be affected. Initial symptoms are of one or more leaves of the middle crown becoming pale-greyish in colour and withering, characteristically affecting pinnae on one side of the leaf first, then the other and developing symptoms from the leaf base to the tip. Meanwhile, on the dorsal side of the leaf, a brown stain appears and spreads from the leaf base to the tip, corresponding to the spread of fungal mycelium inside the vascular tissues. Over a period that can vary between a few days and several weeks, the leaf eventually dies and hangs down alongside the trunk. A progression of other leaves then exhibit the same symptoms, until the terminal bud is killed and the palm dies. Other patterns of symptom expression have been reported (CABI/EPPO, 1997). Death may take 6 months to 2 years after the first appearance of symptoms, depending on the growing conditions and cultivar.
Internal symptoms include a reddish-brown discoloration of infected vascular tissues and surrounding parenchyma and sclerenchyma. Staining has not been reported in the peduncles, flowers or fruit.